This shows the use of ADT drape mass elements for approximate site concepts and also the use of LandXML import to use as a base for ADT buildings. I wouldnt use ADT for complex site work but as a tool for prelimary investigations, or just to put some simple landforms under your building, mass elements can work well. For more complex work we use a consultant with Autodesk Land Desktop & use ADT's LandXML import to get a finished site.
Concept:
For preliminary investigation of sites I have used the Drape Mass element. This is then used with Building and “fill” masses to estimate approximate cut & fill quantities.
Polylines are traced on scanned contour drawings & set at the correct elevation. I find it best to extend them beyond the area to be “draped” even if this requires approximation, as the profile can get a bit lumpy on the edges if only drawn to the boundaries.
Use Mass Element Drape to produce an “oversize” mass.
Create a mass the exact plan shape of the site and intersect with the drape mass to trim off the wobbly edges. You now have a reasonable site contour mass.
Then create mass elements/group to form the building & any fill platforms. These can be subtracted or interfered with the site to calculate approx cut & fill.
We now use this as part of preliminary site investigations where terrain is a factor. It’s only approximate as is dependent on the resolution of the scan, contours, accuracy of tracing and any smoothing errors in the drape calculations. That accepted it’s fast and easy to investigate many more options than is possible with “hand” approximations or educated guesses. It also makes it easy to communicate the impact of schemes with others in the business without requiring them to interpret contour plans and sections.
If you need more accuracy obtain a survey & get the data in LandXML format in addition to the usual drawing.
What is LandXML?
LandXML is a form of Xml used to describe point, parcel & surface data and was developed to allow easy transfer of that data between software applications. You can read a whole lot more about it at http://www.landxml.org. New Zealand has the worlds first online cadastral database system that makes use of LandXML for survey data. Its at http://www.landonline.govt.nz.
As Xml is text based you can read LandXML files in any text/xml editor or web browser but really wouldn’t want to, as they aren’t exactly fun reading. Besides ADT can do it for you!
LandXML and ADT:
ADT 2005 or ADT 2004 with subscription extensions can import LandXML.
You can select what to import:
~ Parcel data imports as AEC Areas.
~ Surface data is used to form a Free Form Mass Element.
~ Points import as points.
~ The Defaults screen allows you to select layer keys for the objects and an area style.
The example shows a 7mb xml file imported into ADT to form a 32 hectare (79 Acre) free form a 6mb mass element! This XML was created by our civil consultant who created some grading options in Autodesk Land Desktop and exported them to LandXML. This one XML file included the original survey and two grading options. ADT imported and created these as separate elements, which we will use as the site for our ADT Project.
LDT & ADT + LandXML allows this seamless collaboration!
This shows some basic building masses on the graded site. Already useful for shadow, sightline, & vehicle access studies.
